The error is pretty clear. you have meshes with animators that are sharing same material. Simply make a new material for each new mesh. You can share the texture(s) if its a TextureMaterial that you need.

If you do not assign the material yourself, and it’s the work of the parser/library
simply generate a new material before addChild the mesh to the scene, reusing the textures from the previous one.

Apparently, when you load a mesh file with no material, a default one is automatically attributed to it, so if you load several files in a row without giving them a new material in between, they will share the default material…